Add StorageIterator

[ixje]

It's added to neo-project but not yet in the smart contract framework so can't use it.
neo-project/neo@a234978f2

[ixje]

Note that I've been able to compile a contract with Storage.Find using this fork however there seem to be 2 issues

1. The iterator cannot be used in a foreach loop due to a missing public definition of GetEnumerator
   

2. prefix searching doesn't seem to work, returns an empty 'list' given the code below

    public class Contract1 : SmartContract
    {
        public static void Main()
        {
            Storage.Put(Storage.CurrentContext, "my_prefixA", "1");
            Storage.Put(Storage.CurrentContext, "my_prefixB", "2");
            Storage.Put(Storage.CurrentContext, "something", "3");
            StorageIterator si = Storage.Find(Storage.CurrentContext, "my_prefix");

            Runtime.Notify("Starting");
            while (si.Next())
            {
                Runtime.Notify(si.Key);
            }
            Runtime.Notify("Done");
        }
    }

[RavenXce]

Yes, I believe the implementation of StorageIterator is bugged. I've been meaning to file a separate issue. I think the key prefix should have a length between it and the scriptHash.

[ixje]

Thanks for the quick handling of the bug in neo-project/neo#200 🥇! Looking forward to see this issue resolved so I can finalise the neo-python implementation with some cross platform tests

[ixje]

hi @erikzhang, you closed this issue but it's actually not resolved yet. Only the neo core Storage.Find implementation is fixed, but this official devpack does not support Storage.Find yet so others cannot use it unless they know about and use the fork from @RavenXce / Switcheo master...ConjurTech:add-apis

[RavenXce]

I will make a PR since it works correctly now.